No one would begrudge NASA's Mars rover Spirit — six years into a mission pegged for 90 days, stuck in sand and lacking power to phone home — retirement.

Instead, in the spirit of making lemonade out of lemons, scientists are preparing a new round of studies uniquely suited for a stuck Mars lander.

"I don't think anyone should have the expectation that this rover is going to go sprinting across the countryside again," lead rover scientist Steve Squyres with Cornell University, said at a Mars exploration strategy session in California last week.

"But there is science that is specially enabled from staying in one place for a long time and it turns out these rovers are pretty good landers," he said.

Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

Silenced since March by low power — the rovers have solar arrays to harvest energy from the sun — Spirit is expected to spring back to life within a month as the Martian spring advances across Gustev Crater, where Spirit landed on Jan. 3, 2004.

An identical twin, Opportunity, touched down three weeks later and remains on the move on the other side of the planet. Both rovers were designed to search for signs of past water, believed to be a key ingredient in the recipe for life.

Spirit's final resting place may turn out to be a gold mine. The rover sits in an area called Troy on the lip of a small crater located west of Home Plate in Gusev Crater. Crippled by two broken wheels — it started off with six — the rover has been unable to extricate itself from the slippery sand, which is laced with water-soluble minerals.

"It's not a coincidence that we got stuck where we did. This soil here is bizarre. It's weird, it's different and it is fascinating in its chemistry and mineralogy," Squyres said. "We have the opportunity to really hunker down on a spot of soil that's really interesting and understand it in detail."

Scientists believe they are seeing the effects of trickling water, with layers of deposits.

"There is a wealth of materials here," Squyres said. "And we have a testable hypothesis here of what might be going on."

Another set of experiments, overseen by rover project scientist Bruce Banerdt with NASA's Jet Propulsion Laboratory in California, will attempt to zero in on what's inside the planet.

Scientists don't know much about Mars' core, whether it is solid, liquid or a combination of the two. With Spirit stationary, its communications signal can be used as beacon to precisely track the planet's spin. Over a period of months, that information can be used to deduce the size of Mars' core.

Banerdt said the radio science experiment would work even if Spirit could travel several meters, a scenario Squyres deemed highly unlikely. "We were having a tough time driving with five wheels, and with four wheels going long distances is pretty much out of the question," he said.

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Rounding out Spirit's new science agenda are studies of how the atmosphere interacts with ground.

"If you're moving all the time, you find some interesting feature and then you leave it and you never see it again," Squyres said.

Or, the rover gets it in view again, but the angle is different or the lighting has changed, so you can't differentiate between visual effects and actual changes in the atmosphere, he added.

Spirit has instruments that can look at dust storms and other atmospheric phenomena from both microscopic and broad-view perspectives.

Of course, Spirit's new campaign depends on the rover reviving from its prolonged winter hibernation. The crippled craft was unable to position itself to pick up much of the winter's sun, so scientists don't know how long it will take for the rover to recharge.

Based on the temperatures the rover was expected to experience, it should have been able to recharge itself by September or October.

It's also possible that the rover's master clock was shut down by the cold, in which case Spirit's recovery could take months, Squyres said.

"My money is still on that vehicle coming back to life and my guess is that it's probably going to happen in the next month," he said.

The face of Mars

The Hubble Space Telescope focuses on the full disk of Mars, with a head-on view of a dark feature known as Syrtis Major. Hubble astronomers could make out features as small as 12 miles wide.
(AURA / STSCI / NASA)
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Red, white and blue planet

Two decades before Pathfinder, the Viking 1 lander sent back America's first pictures from the Martian surface. This 1976 picture shows off the lander's U.S. flag and a Bicentennial logo as well as the planet's landscape.
(NASA)
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Grand canyon

This is a composite of Viking orbiter images that shows the Valles Marineris canyon system. The entire system measures more than 1,875 miles long and has an average depth of 5 miles.
(NASA)
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Red rover

A mosaic of eight pictures shows the Pathfinder probe's Sojourner rover just after it rolled off its ramp. At lower right you can see one of the airbags that cushioned Pathfinder's landing on July 4, 1997.
(NASA)
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Twin Peaks at their peak

The Pathfinder probe focuses on Twin Peaks, two hills of modest height on the Martian horizon. Each peak rises about 100 feet above the surrounding rock-littered terrain.
(NASA)
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Blue horizon

A Martian sunset reverses the colors you'd expect on Earth: Most of the sky is colored by reddish dust hanging in the atmosphere, but the scattering of light creates a blue halo around the sun itself.
(NASA / JPL)
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Two-faced Mars

The image at left, captured by a Viking orbiter in the 1970s, sparked speculation that Martians had constructed a facelike monument peering into space. But the sharper image at right, sent back in 1998 by Mars Global Surveyor, spoiled the effect.
(NASA)
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A monster of a mountain

Mars' highest mountain, an inactive volcano dubbed Olympus Mons, rises as high as three Everests and covers roughly the same area as the state of Arizona. Mars Global Surveyor took this wide-angle view.
(MSSS / NASA)
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From Mars with love

This valentine from Mars, as seen by Mars Global Surveyor, is actually a pit formed by a collapse within a straight-walled trough known in geological terms as a graben. The pit spans 1.4 miles at its widest point.
(MSSS / NASA)
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Sandy swirls

An image taken by Mars Global Surveyor shows a section of the northern sand dunes on Mars' surface. The dunes, composed of dark sand grains, encircle the north polar cap.
(JPL / NASA)
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Curls of clouds

Global Surveyor focuses on a storm system over Mars' north polar region. The north polar ice cap is the white feature at the top center of the frame. Clouds that appear white consist mainly of water ice. Clouds that appear orange or brown contain dust.
(MSSS / NASA)
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Swiss cheese

Global Surveyor captured images of a frost pattern at Mars' south polar ice cap that looks like Swiss cheese. The south polar cap is the only region on the Red Planet to contain such formations.
(NASA / JPL / Malin Space Science)
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Purple Planet

A false-color image from the Opportunity rover, released Feb. 9, 2004, accentuates the differences between a green-looking slab of Martian bedrock and orange-looking spheres of rock. Scientists likened the "spherules" to blueberries embedded within and scattered around muffins of bedrock. The spherules are thought to have been created by the percolation of mineral-laden water through the bedrock layers.
(NASA / JPL / Cornell University)
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Dunes of Mars

A false-color view from NASA's Opportunity rover, released Aug. 6, 2004, shows the dune field at the bottom of Endurance Crater. The bluish tint indicates the presence of hematite-containing spherules ("blueberries") that accumulate on the flat surfaces of the crater floor.
(NASA / JPL / Cornell University)
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Alien junkyard

The Opportunity rover looks at its own heat shield, which was jettisoned during the spacecraft's descent back in January 2004, on Dec. 22, 2004. The main structure from the heat shield is at left, with additional debris and the scar left by the shield's impact to the right. The shadow of the rover's observation mast is visible in the foreground.
(NASA / JPL)
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Devil on Mars

This image shows a mini-whirlwind, also known as a dust devil, scooting across the plains inside Gusev Crater on Mars, as seen from the Spirit rover's hillside vantage point on April 18, 2005.
(NASA / JPL)
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Rub al Khali

The tracks of NASA's Opportunity rover are visible in a panoramic picture of a desolate, sandy stretch of Martian terrain in Meridiani Planum, photographed in May 2005 and released by NASA on July 28. "Rub al Khali" (Arabic for "Empty Quarter") was chosen as the title of this panorama because that is the name of a similarly barren, desolate part of the Saudi Arabian desert on Earth.
(NASA / JPL / Cornell University)
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Double moons

Taking advantage of extra solar energy collected during the day, NASA's Spirit rover spent a night stargazing, photographing the two moons of Mars as they crossed the night sky. The large bright moon is Phobos; the smaller one to its left is Deimos.
(NASA / JPL / Cornell / Texas A&M)
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Mars in the round

A 360-degree panorama shows a stretched-out view of NASA's Spirit rover and its surroundings on the summit of Husband Hill, within Mars' Gusev Crater. The imagery for the panorama was acquired in August, and the picture was released on Dec. 5.
(NASA)
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Fossil delta

Scientifically, perhaps the most important result from use of the Mars Orbiter Camera on NASA's Mars Global Surveyor has been the discovery in November 2003 of a fossil delta located in a crater northeast of Holden Crater.
(NASA / JPL / MSSS)
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Underneath the ice

This view taken in January 2005 shows sharp detail of a scarp at the head of Chasma Boreale, a large trough cut by erosion into the Martian north polar cap and the layered material beneath the ice cap.
(NASA / JPL / MSSS)
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Celestial celebration

Controllers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., cheer on Friday after hearing that Mars Reconnaissance Orbiter successfully made it into orbit around the Red Planet.
(Phil McCarten / Reuters)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.